Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine vane and blade assemblies to these high temperatures. As a result, turbine blades, vanes, and combustion components must be made of materials capable of withstanding such high temperatures. In addition, turbine blades, vanes, and combustion components often contain cooling systems for prolonging the life of the blades and vanes, reducing the likelihood of failure as a result of excessive temperatures.
Typically, turbine blades are formed from a root portion and a platform at one end and an elongated portion forming a blade that extends outwardly from the platform. The blade is ordinarily composed of a tip opposite the root section, a leading edge, and a trailing edge. Turbine vanes are typically formed from an elongated portion forming a blade that extends between two platforms, one platform on each end. Conventional turbine blades and vanes have many different designs of internal cooling systems. Generally, the inner aspects of most turbine blades and vanes typically contain an intricate maze of cooling channels forming a cooling system, or cooling network and these components exposed to hot combustion gases are cooled by passing a cooling fluid, such as compressed air bled from a compressor of the gas turbine, through a hollow interior of the component. Cooling air from the compressor of the gas turbine engine is passed through the blades and vanes, and they are cooled convectively. Because the cooling air coming from the compressor is unfiltered, it often includes a multitude of microscopic particles such as dust or dirt. The cooling channels, which often include multiple flow paths that are designed to maintain all aspects of the turbine blade or vane at a relatively uniform temperature have been sufficiently large to pass the microscopic particles.
As cooling technology improves, as well as the high temperature metallurgical properties of many of the materials used to fabricate cooled turbine components, the volume of cooling air required for cooling is decreased which ultimately leads to an overall increase in efficiency of the gas turbine engine. With the decrease in volume of cooling flow circulating through the cooling maze, a reduction in the cooling channel size is realized. However, ingestion of microscopic particles poses one of the most significant limitations to turbine engine component cooling effectiveness and durability. The microscopic particles routed through cooling passages in the turbine blades and vanes can accumulate over time blocking the cooling air flow and cover the surfaces with an insulating particle layer that reduces cooling effectiveness. Additionally, any corrosive substances in the particles may chemically react with the base alloy at the high turbine operating temperatures, thereby corroding the surfaces. Over time, continued particle accumulation can lead to failure of the turbine blades and vanes. The most common symptom of such component failure is a large performance decrease, resulting in premature removal of the engine for low power output. Occasionally, symptoms are not observed until there is a failure of the turbine with extensive secondary damage to the engine resulting in high repair cost. Thus, an internal cooling system having an increased ability to filter microscopic particles from cooling air flow is needed.